Flow properties affecting steel pipe material assessment

The simulation of transient flows in pipeline system engineering is often concerned with the analysis of extreme temperature conditions, quite lower or higher than normal operation ones. This kind of simulations is performed to verify that the system size, determined with reference to steady operation, can withstand such different scenarios. Furthermore, these extreme conditions can dictate the requirements for design data and hence material selection. Gas pipeline system depressurizations are the typical conditions for achievement of low temperature; venting facilities are normally sized by using materials different from normal carbon steel, suitable for such temperatures. On the other side, quite high temperatures can be generated during the a thermal treatment called Post-Weld Heat Treatment, performed in some cases to release residual stresses from welding. Those conditions can be detrimental for the integrity of the coating material that may have high temperature limitations. Finally, other integrity issues treated in this chapter are relevant to a potential pipeline ductile fracture propagation following a rupture; in this case, the engineering analysis can determine the material toughness requirements to avoid this risk.